Savandaiah Chethan, Sieberer Stefan, Plank Bernhard, Maurer Julia, Steinbichler Georg, Sapkota Janak
Bio-Based Composites and Processes, Wood K Plus-Kompetenzzentrum Holz GmbH, 4040 Linz, Austria.
Institute for Polymer Injection Moulding and Process Automation, Johannes Kepler University, 4040 Linz, Austria.
Polymers (Basel). 2022 Apr 29;14(9):1838. doi: 10.3390/polym14091838.
Composite filament co-extrusion (CFC) additive manufacturing (AM) is a bi-matrix rapid fabrication technique that is used to produce highly customisable composite parts. By this method, pre-cured, thermoset-based composite carbon fibre (CCF) is simultaneously extruded along with thermoplastic (TP) binding melt as the matrix. Like additive manufacturing, CFC technology also has inherent challenges which include voids, defects and a reduction in CCF's volume in the fabricated parts. Nevertheless, CFC AM is an emerging composite processing technology, a highly customisable and user-oriented manufacturing unit. A new TP-based composites processing technique has the potential to be synergised with conventional processing techniques such as injection moulding to produce lightweight composite parts. Thus, CFC AM can be a credible technology to replace unsustainable subtractive manufacturing, if only the defects are minimised and processing reliability is achieved. The main objective of this research is to investigate and reduce internal voids and defects by utilising compression pressing as a rapid consolidation post-processing technique. Post-processing techniques are known to reduce the internal voids in AM-manufactured parts, depending on the TP matrices. Accordingly, the rapid consolidated neat polylactic acid (PLA) TP matrix showed the highest reduction in internal voids, approximately 92%. The PLA and polyamide 6 (PA6) binding matrix were reinforced with short carbon fibre (SCF) and long carbon fibre (LCF), respectively, to compensate for the CCF's fibre volume reduction. An increase in tensile strength (ca. 12%) and modulus (ca. 30%) was observed in SCF-filled PLA. Furthermore, an approximately 53% increase in tensile strength and a 76% increase in modulus for LCF-reinforced PA6 as the binding matrix was observed. Similar trends were observed in CFC and rapidly consolidated CFC specimens' flexural properties, resulting due to reduced internal voids.
复合长丝共挤（CFC）增材制造（AM）是一种双基体快速制造技术，用于生产高度可定制的复合材料部件。通过这种方法，预固化的、基于热固性的复合碳纤维（CCF）与热塑性（TP）粘结熔体作为基体同时挤出。与增材制造一样，CFC技术也存在固有的挑战，包括孔隙、缺陷以及制造部件中CCF体积的减少。尽管如此，CFC AM是一种新兴的复合材料加工技术，是一个高度可定制且以用户为导向的制造单元。一种新的基于TP的复合材料加工技术有可能与传统加工技术（如注塑成型）协同作用，以生产轻质复合材料部件。因此，只要将缺陷最小化并实现加工可靠性，CFC AM就可以成为替代不可持续的减材制造的可靠技术。本研究的主要目的是通过将压缩压制作为一种快速固结后处理技术来研究并减少内部孔隙和缺陷。后处理技术已知可减少增材制造部件中的内部孔隙，这取决于TP基体。相应地，快速固结的纯聚乳酸（PLA）TP基体显示出内部孔隙减少最多，约为92%。PLA和聚酰胺6（PA6）粘结基体分别用短碳纤维（SCF）和长碳纤维（LCF）增强，以补偿CCF的纤维体积减少。在SCF填充的PLA中观察到拉伸强度（约12%）和模量（约30%）有所增加。此外，观察到以LCF增强的PA6作为粘结基体时，拉伸强度增加约53%，模量增加76%。在CFC和快速固结的CFC试样的弯曲性能中也观察到类似趋势，这是由于内部孔隙减少所致。
